The statements in this section merely provide background information related to the present disclosure. Accordingly, such statements are not intended to constitute an admission of prior art.
Known powertrain systems are configured to transfer torque from a torque actuator through a transmission device to an output member coupled to a driveline to effect propulsion of a vehicle. A powertrain system may be configured to transfer torque originating from multiple torque actuators through a multi-mode transmission device to an output member coupled to a driveline to effect propulsion. Such powertrain systems include hybrid powertrain systems, extended-range electric vehicle systems, and, electric vehicle systems. Control systems for operating such powertrain systems operate the torque actuators and apply selected torque transfer elements in the transmission to transfer torque in response to operator-commanded output torque requests, taking into account fuel economy, emissions, driveability, and other factors. Exemplary torque actuators include internal combustion engines and non-combustion torque machines. The non-combustion torque machines may include electric machines that operate as motors or generators to generate torque input to the transmission independently of torque input from the internal combustion engine. The torque machines may react torque, i.e., transform vehicle kinetic energy transferred through the vehicle driveline to electrical energy that is storable in an electrical energy storage device in what is referred to as a regenerative operation. A control system monitors inputs from the vehicle and the operator and provides operational control of the powertrain, including controlling an engine on/off state, controlling a transmission operating state, controlling the torque actuators, and regulating electrical power flow between the electrical energy storage device and the electric machines to manage transmission operation including torque and rotational speed.
Components employed in hybrid powertrain systems have operating limits that are determined based upon a physical capacity to perform an intended function, including, e.g., transferring torque, transferring electric power, or storing electric energy. Service life of a component may be reduced if a respective operating limit is violated. Operating limits include electric motor speed limits, engine speed limits, pinion gear speed limits of planetary gear sets, and battery power limits. Operating limits further include motor torque limits, engine torque limits, clutch torque limits, and belt torque limits. Operating limits also include electric limits including voltage and current limits. By way of example, service life of a high-voltage battery may be limited if either over-voltage or under-voltage limits are exceeded. Similarly, a service life of a switch in an electric inverter may be limited if an operating temperature is exceeded. Similarly, service life of a hydraulically activated clutch may be limited if an operating pressure is exceeded.
Control systems for hybrid powertrain systems impose system constraints based upon the operating limits to determine control parameters for operation during ongoing operation.